IK Rotation option for opposite end
This effect can be done by reversing the IK string ([w] -> "Switch bone direction") and placing the IK constraint on the "first" bone targeting the bone that used to come before it. Give the "last" bone (that used to have the IK constraint) a Copy Transforms constraint of the old IK target.

However, there are a couple things wrong with this method:


If the target is brought outside of the maximum length of the bones, instead of the bones pointing toward the target, they will follow the target and point at the other bones.
The rotation of the new target must be accounted for.